Colored glass fibers and method of producing the same



Feb. 25, 1958 H. J. HOMER ETAL COLORED GLASS FIBERS AND METHOD OF PRODUCING THE SAME Filed May 12, 1955 HOWARD J. HOMER y JOHN R. WHITACRE 7 nm' ATTORNEY ire tes COLORED GLASS FIBERS AND -METHOD OF PRODUCING THE SAME Application May 12, 1955, Serial No. 507,828

3 Claims. Cl. 204-20 This invention relates to glass fiber products and materials and is particularly concerned with colored glass fibers and methods of producing the same.

A primary object of the invention is to provide on glass fibers a surface which is receptive to coloring agents and which cooperates with ordinary coloring agents, such as dyes and pigments, to permanently color the fibers.

A further object of the invention is to produce colored glass fibers without sacrificing the desirable characteristics of the fibers and which colored glass fibers have improved abrasion resistance.

' An important object of the invention is to provide novel methods for the production of colored glass fibers.

In the practice of the invention the glass fibers, provided in strand or fabric form, are coated thereover with a layer of aluminum metal which is then anodized to form aluminum oxide; the anodized coated fibers are then dyed and the product is sealed preferably by subjecting the dyed material to a hot aqueous treatment which converts the aluminum oxide to hydrated aluminum oxide. This conversion causes an increase in volume and a compacting of the material and effectively closes the pores and thus assists in dye retention and prevents further dyeing of the material.

Treatment to produce the aluminum coating on th glass fibers is carried out by heating the fibers to at least the thermal decomposition point of a heat decomposable aluminum bearing gaseous compound and contacting the heated fibers with such a gas.. Aluminum tri-methyl, triethyl or tri-propyl are very suitable and in general compounds of the formula A1(R) wherein R represents any alkyl radical of low molecular Weight, preferably below 6 carbon atoms, are useful; combinations of the'aluminum alkyls such'as Al(R R R may be utilized. If the pressure is maintained low during the deposition the aluminum aryls such as the phenyl or benzyl may be employed.

The treatment with the aluminum compound may be effected in conjunction with the formation of the'fibers or subsequent to the formation of the fibers into products such as glass cloth. For appropriate adhesion of the aluminum to the fibers it is best to remove any lubricant or size by heat treatment or solvent washing prior to exposure to the gaseous atmosphere.

.. -The aluminumcoating is anodized in a suitable acid bath to. produce a, surface receptive to dyeing, Most l arenr suitably the anodizing solution is sulfuric acid although chroinic acid may also be employed. The anodized fibers should be washed completely free of acid in order that the subsequent dyeing operation will not be impeded.

" v The dyeing, that is the coloring agent, may be selected 'from those customarily employed in the dyeing of teX- 1 The sealing or closing of thepore's of. the dyed anodto decrease the slight friction effects between the ized material is most important and suitably effected with an aqueous medium at temperatures of to 200.

F. This sealing-bath preferably contains an agent to inhibit leaching of the dye during sealing; a concentration of about 0.5% of nickel acetate is effective for this purpose. I

The sealing operation causes the dyed anodized aluminum or aluminum oxide to be converted to an aluminum hydrate. The pick-up of the water results in a volume increase, pore closing being efiected with the result that dye leaching is prevented and the material is no longer susceptible to dyeing.

The effectiveness of the procedure is'considered attributable to the purity of the aluminum deposit obtained by plating the heat decomposable gaseous compound. Aluminum when alloyed with other metals does not respond as well to the dyeing procedurefor the fibers.

The invention will be more fully understood by reference to the following detailed description and accompanying drawing wherein:

Figure 1 schematically illustrates apparatus useful in the practice of the invention; and I Figure 2 is a cross-sectional view on an enlarged seal of a filament produced in accordance with the invention.

Referring to Fig. l the numeral 1 indicates a reel having thereon a bundle of glass fiber rovings 3. A roving consists of a large plurality of filaments which are parallel laid and are of a substantially continuous length; each filament may have a diameter of about 9 microns for example and the roving may contain 204 of these filaments, while a roving bundle may, as at 3, comprise ,suitably 8 rovings. Such rovings are commercial items.

The numeral 5 indicates an oven through which the roving bundle is passed; this oven is effective to remove lubricant from the fibers and normally operates at a temperature of between 300 and 600 F. With some binderlubricants, particularly those containing starch, it may be preferable to remove the binder prior to initiating the process to avoid an unduly slow rate of roving speed; however in some instances the filaments may be formed without hinder or lubricant application and the oven may then be dispensed with.

The numeral 7 indicates a heating chamber; this comprises a pair of rectangular blocks 9, 11 the lower one of which is slotted longitudinally over a central portion of the width to provide a passageway of somewhat greater thickness than the rovings. The base wall 12 of the pars sageway is smooth surfaced to permit the rovings to slide thereover.

The numeral 13 indicates an electrical resistance heat er element buried in the lower block 11 and which element has leads 15, 17 connected to a source of voltage. The blocks themselves are provided with a covering insulation shown at 19 and hence the base wall 12 is heated and the roving filaments sliding thereover are similarly heated. in this embodiment the fibers are heated to approximately 525550 F. Where the oven 5 is utilized and the oven is closely positioned to the chamber 7 the heat of the oven assists in attaining the required temperature which of course is below the softening point of the material.

A conduit 21 communicates from the exterior with the passageway and a heavy flow of inert gas such as nitrogen, or carbon dioxide, is passed through the conduit to the passageway and flows leftwardly (Fig. 1) to seal the interior of the passageway from the atmosphere. Accordingly the'ine'rt gas flow is preferably at least slightly above atmospheric pressure. Such gas flow counter- .current to the roving bundle moving through the slot tends roving bundle and the base wall 12. i

The righthand end ofthe heating chamber 7 is 'cooled over a short'space to a temperature belowthat at which the gaseous aluminum bearing compound will decompose to deposit metal. This prevents deposition of metal;

af the chamber extremity. The .cooling ise'ffected {by passing cooling water from inlet 23 to outlet lithrough conduit interconnected holesbored iii the'ble'ck'ends.

. j The plating chamber 27jis directly'secured to the heating chamber'7 and ts an enlarged spacing through which the plating gas flows from inlet 29 toward outlet 31. .As

noted the end of heating chamber -7 which'borders the plating chamber 27 is cooled and no deposition occurs in the heating chamber. fln this connection it is to be noted that the gas pressure within thepassageway'of the heating chamber tends to prevent any plating gas flow into the passageway itself. Further the roving *thickne'ss'is V considerable and-tends tobloclg the passageway and the roving-movementitsdf assists to prevent plating gas flow into the heating chamber;

The plating gas of the present embodiment may be. aluminum tri-methyl and the vapors entering the plating i chamber- 27 through inlet 29 are suitably at a tempera- Y ture of 325-350 F. When this gasistrikes the filaments.

the gas decomposes depositing metal on the filaments; the

organic gaseousfragments beingdrawn out'through out- 7 let-31. The plating gas itself is preferably at 'substan tially atmospheric pressure and the; pressure and flow rate of the gas maybe varied to attain a desired, coati g thickness on'the' roving filaments. Suitably atatmos V pheric pressure 4 6 cubic feetper minute of plating gas may be passedinto the chamber when the roving bundle; is moving at a lineal speed of l to 2 feet per minute. ,The pressure,- flow rate and speed maybe varied however in accordance with specific .operatingcQnditi nSJ .elirm natedf The heating and the aluminumcoating do not noticeably alterthe flexibility of the fibers and 1 the roving bundle in compact relation passes throughoutlet open- 45 ing 33 to anodizing bath 3S. 1

" 'Referring briefly to Fig. 2 theindividual filamentof the roving bundle "as it passes to the anodizing bath has a preferably a very thin coating of aluminumapproacb ing. the monomolecular; the coating'is indicated by. the

numeral37i in Fig. 2. 'f a 1 1 The tank 35 is lead lined on the' interior and the lining functions as' a' cathode in the anodizing process which takes place in tank 35. Suitably mo'unted 'in thetank' area plurality of ,m'etalpulleys 37 over which the 'aln'mi-' nized 'filaments pass. suitably 'connectedbetween the interior of the tank and pulley37 by lead wires 39;:41

isIa source ofjvoltage indicated by the letter V,the pul1ey '1 37 {being connected .to the'positive pole of the directed.

current source. a V :7 l Most suitably the tank '35 contains sulphuric acid at. a

V temperatiireof -608 F. and.the concentration of 'sul phuric acid is preferably about,l 20% by'weightpThe current density may be .suitably varied between -25 V am p ip'er square, foot. 'The time of treatment inlthe' present instance with the above noted conditions may. be

approximately twelve minutes...

{Theianodizin'g treatment converts. the aluminumecoab f ing ito aluminum oxide and this forms areceptivesurface :forthesubsequent dyeing operation. i

It is tofbeparticularly'noted.that the aluminum as. it'

passes into theltzink35 is in .a very pure; state sinceit '1' has-been -:.deposited from. the'fgaseous-aluminum hearing .ggdmpound; :The pure Jstatebf '-the. .-material is .fmost f portant to the realization of optiinum conditions"ofldye 75 :coating to form aluminurhi oxide; 1 dyeing tlieanodized feifectsfiv 7 a 1 a I 40. 'ltisto be noted thatthespeed of operation is reduced 1 somewhat, bythe necessity for the long anodizing and f 1 dyeing times; The operation may of courseEbeZ performed ing as Well as. for anodizing. The brightest and clearest anodic film is obtained when the aluminum is pure whereas alloyed deposits containing even high'percentages of aluminuindo not approach the-result of that attained 5 by pure metal.

'From tank 35 the anodized material'passes' to a wash tank 43 which contains cool .Wa'ter'and which tank'has suitably mounted therein pulleys 45 for thepassage of the 'aluminized roving bundle; 'It is essential thatlth egacid 10 be completely removed prior to dyeing'and accordingly the filamentary bundle is wound a series of times through the tank and the waterof such tankshould-be changed frequently or may. as 'desired'be' cireul'ated. I

The washing iscompleted most sultablyj by passing: the bundlefovei" pulleys 47in tower 49;'spray' heads.- 51

'thoroughly Washing the' 'last vestigesjof acid from the roving bundle. The completely washed bundle passes centration ofnickel acetate to the extentot about 0.5%. 1 by weightrw'lhe temperature ofthis water is maintained l at about"1809-200 F. and the effectof thisjtreatment is to cause'the aluminum oxide to be converted to an alu- -minum hydrate. Thus anyporosity present in the anod-' ized film will'be sealedfb y the-treatment in 'tank 51f as the materials pass over pulleys :59 and the dye in the 1 vpor esvvill be elosed in preventing' leaching of the "dye a and also inhibiting further; dyeing of the'material. The st n e woun p on a a fi e s is ead for formation into finished articlesj including laminated materials; for example,- transparent plastics may be laminated with'the dyed glass fibers .to produee novel-visual batch-wise and need not'be a continuous process 'as shown in Fig. 1.... On a continuousbasis the ispeeddepends upon the (length and arrangement of the tanks-35.43, 5 3 and 57. Under the circumstances describedabove f wherein the speed of the roving strand isaboutone foot per minute, the length o fithe tank niay be materially 10 feet per minute or higher smeared! I It will beunderstood that'this inv 'ntlonls t' the scope of. the; appended claim'g': I

We 'claimz'i hend such modifications within this invention as maygr il 7 11,.1Theizhethod of coloring, glass fibers which consists .incontactingheated glass fiber surfaces at atmospheric pressure with aheat decomposable'organic salt having the I formula [Al(R) 3 whe'reinR'is a'i adieal;selected from the V group consisting of methyl; ethyl and prop'yl to deposit af coatingjof aluminum" on-fthe fiber surfacjes, anodi zingithe ;coating to f orm aluminum oxide',fdyeing the anodized l V coating, andfthen 'subjectingfthe,dyedjcoatingtopai'hot M 'aqueous treatment tofhyd'rate"thelaluminum oxiderall while maintaining the fibersflexibll I to tank 53 which contains a dye solution, for example, a' V 0.2 to 0.6% by weight of mcthyleneblue. 'Ihe'solution '20 'offthe bath is held at a temperature of; 150? F. and the bundle is passed overpulleysSS in a serpentine path'to insure the completion of the dyeing operation; 1 Custo- I marily an exposure time; of sixty minutes'is satisfactory to elfect dyeing...:The dyfed material thenffpasses to a 25 bath 57 which contain's' waterlpreferably having-a con- 7 reduced by'winding the filam'ent'slhrough in serpentine 5 fashion. With' considerable eonipaction of the pulley arrangement the speed of operation may. readily .be8'jto susceptible 2. The method ofeoloiring glass fibers which cons ists I V in contacting heated glass fiber surfacesunderivactiumf ,conditions with-aheat decomposable organicisalt having V the generalfor l A (R")3. h isi r u s'aa adi ali ,5; s ed h -s io p'of hen y an pheny1;to. n $1t a 1 coating of aluminum on the fiber;surface's'; anodizingthq coating, and then subjecting the dyed coating to a hot aqueous treatment to hydrate the aluminum oxide, all while maintaining the; fibers flexible.

3. The method of'coloring glass fibers which comprises contacting heated glass fiber surfaces at a vacuum to an atmospheric pressure with a heat decomposable organic salt of aluminum having the general formula Al(R) wherein R is a radical selected from the group of lower aliphatic and aryl radicals to deposit a coating of aluminum on the fiber surfaces, anodizing the coating to form aluminum oxide, dyeing the anodized coating, and then subjecting the dyed coating to a hot aqueous treatment to hydrate the aluminum oxide, all while maintaining the fibers flexible.

References Cited in the file of this patent UNITED STATES PATENTS Francon Oct. 11, 1938 Guild Ian. 9, 1940 Lawton Jan. 2, 1951 Brennen Nov. 4, 1952 Davis et a1 NOV. 25, 1952 Godley Dec, 16, 1952 France et a1. July 6, 1954 Nachtman Jan. 11, 1955 Wainer et a1 June 28, 1955 Toulmin May 1, 1956 

3. THE METHOD OF COLORING GLASS FIBERS WHICH COMPRISES CONTACTING HEATED GLASS FIBER SURFACES AT A VACUUM TO AN ATMOSPHERIC PRESSURE WITH A HEAT DECOMPOSABLE ORGANIC SALT OF ALUMINUM HAVING THE GENERAL FORMULA A1(R)3 WHEREIN R IS A RADICAL SELECTED FROM THE GROUP OF LOWER ALIPHATIC AND ARYL RADICALS TO DEPOSIT A COATING OF ALUMINUM ON THE FIBER SURFACES, ANODIZING THE COATING TO FORM ALUMINUM OXIDE, DYEING THE ANODIZED COATING, AND THEN SUBJECTING THE DYED COATING TO A HOT AQUEOUS TREATMENT TO HYDRATE THE ALUMINUM OXIDE, ALL WHILE MAINTAINING THE FIBERS FLEXIBLE. 